1. Technical Field
The present invention relates to an actuator, an optical scanner and an image forming device.
2. Related Art
An optical scanner is embedded in a laser printer or the like. The optical scanner is used for drawing an image through optical scanning. JP-A-2004-191953 is an example of related art. The example discloses an optical scanner that has an actuator using a torsional vibrating element. The actuator (optical scanner) according to the example has a torsional vibrating element of a single-degree-of-freedom vibration system. More specifically the actuator has a movable plate (a reflecting mirror part) which is supported by a support part (a fixing frame) through an axial part (a spring part) such that the movable plate is rotatable with respect to the support part.
The movable plate rotates when the axial part is distorted and deformed. Light is reflected at the light reflecting part and scanning is performed. In this way, an image can be drawn through the optical scanning.
In the actuator according to the example, weight of the movable plate and a spring constant of the axial part are fixed so that the actuator can only be driven at a given resonance frequency once it is fabricated. This means if the weight of the movable plate and the spring constant of the axial part become different from a design value of the actuator, the resonance frequency also becomes different from a desired value. For this reason, it is difficult to obtain an actuator that has a desired rotating-motion characteristic.